Technical Field
The present invention relates to a nozzle plate, liquid droplet discharge head, and liquid droplet discharge apparatus.
Background Art
A display or a semiconductor integrated circuit includes a substrate and a plurality of patterned films of electronic materials laminated on the substrate. In the background art, the photolithographic method is used for high definition patterning, and recently, the patterning process has been implemented by a printing process in the closely watched field of printed electronics.
In printed electronics, several discrete printing processes are used, including screen printing, gravure printing, and micro-contact printing. An inkjet method is one of those processes.
In the inkjet method, an inkjet recording apparatus including an inkjet head to discharge liquid droplets of ink, for example, is used. The inkjet head includes a nozzle, from which liquid droplets are discharged, impacted onto a printing object, and printing is performed.
A typical inkjet head includes a nozzle face, discharge ports disposed on the nozzle face, nozzle holes as through-holes and spaces communicating with the nozzle holes in a depth direction, and a nozzle plate to form an ink liquid chamber communicating with each nozzle hole.
The inkjet head is configured to selectively discharge liquid droplets from the discharge port by applying force from a driving means to an ink meniscus formed at the discharge port. As driving means for the inkjet head, there are an electrostatic aspiration type, a piezoelectric type using a piezoelectric element, and a thermal type employing a thermal element.
In printed electronics, a high resolution of from submicrons to 10 μm is required to print circuit wiring of the electronic device, so that the application of the inkjet method of the electrostatic absorption type capable of discharging ultrafine liquid is being studied.
In the inkjet method of the electrostatic absorption type, a liquid droplet is electrically charged and then discharged onto a print object by electrostatic induction. As a result, when the print object is an insulating material, due to application of voltage from the drive electrode that charges the liquid droplet, electrical charge is accumulated on the surface of the print object due to aerial discharge from a tip end of the nozzle or from the nozzle plate, and the surface potential increases, destabilizing the potential difference between the nozzle plate and the print object and resulting in a discharging failure.
In one inkjet method of the electrostatic absorption type, a discharging member with a plurality of openings is disposed between the nozzle face of the inkjet nozzle and the surface of the print object. The ink liquid droplet discharged from the nozzle is contacted to the discharging member to be permeated by the discharging member, to be impacted to the print object.
In another inkjet method, an X-ray generator is disposed, and the print object is neutralized by irradiation with X-rays. As a result, the discharged ink is not affected by the electrical charge of the print object and the ink is impacted at a desired position.